nsLineBreaker.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- *//* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is Novell code. * * The Initial Developer of the Original Code is Novell. * Portions created by the Initial Developer are Copyright (C) 2006 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Robert O'Callahan <robert@ocallahan.org> (Original Author) * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */#ifndef NSLINEBREAKER_H_#define NSLINEBREAKER_H_#include "nsString.h"#include "nsTArray.h"#include "nsILineBreaker.h"class nsIAtom;
/** * A receiver of line break data. */00050class nsILineBreakSink {
public: /** * Sets the break data for a substring of the associated text chunk. * One or more of these calls will be performed; the union of all substrings * will cover the entire text chunk. Substrings may overlap (i.e., we may * set the break-before state of a character more than once). * @param aBreakBefore the break-before states for the characters in the substring. */virtualvoidSetBreaks(PRUint32 aStart, PRUint32 aLength, PRPackedBool* aBreakBefore) = 0;
/** * Indicates which characters should be capitalized. Only called if * BREAK_NEED_CAPITALIZATION was requested. */virtualvoidSetCapitalization(PRUint32 aStart, PRUint32 aLength, PRPackedBool* aCapitalize) = 0;
};
/** * A line-breaking state machine. You feed text into it via AppendText calls * and it computes the possible line breaks. Because break decisions can * require a lot of context, the breaks for a piece of text are sometimes not * known until later text has been seen (or all text ends). So breaks are * returned via a call to SetBreaks on the nsILineBreakSink object passed * with each text chunk, which might happen during the corresponding AppendText * call, or might happen during a later AppendText call or even a Reset() * call. * * The linebreak results MUST NOT depend on how the text is broken up * into AppendText calls. * * The current strategy is that we break the overall text into * whitespace-delimited "words". Then those words are passed to the nsILineBreaker * service for deeper analysis if they contain a "complex" character as described * below. * * This class also handles detection of which characters should be capitalized * for text-transform:capitalize. This is a good place to handle that because * we have all the context we need. */00090class nsLineBreaker {
public:
nsLineBreaker();
~nsLineBreaker();
staticinline PRBool IsSpace(PRUnichar u) { return NS_IsSpace(u); }
staticinline PRBool IsComplexASCIIChar(PRUnichar u)
{
return !((0x0030 <= u && u <= 0x0039) ||
(0x0041 <= u && u <= 0x005A) ||
(0x0061 <= u && u <= 0x007A));
}
staticinline PRBool IsComplexChar(PRUnichar u)
{
return IsComplexASCIIChar(u) ||
NS_NeedsPlatformNativeHandling(u) ||
(0x1100 <= u && u <= 0x11ff) || // Hangul Jamo
(0x2000 <= u && u <= 0x21ff) || // Punctuations and Symbols
(0x2e80 <= u && u <= 0xd7ff) || // several CJK blocks
(0xf900 <= u && u <= 0xfaff) || // CJK Compatibility Idographs
(0xff00 <= u && u <= 0xffef); // Halfwidth and Fullwidth Forms
}
// Break opportunities exist at the end of each run of breakable whitespace// (see IsSpace above). Break opportunities can also exist between pairs of// non-whitespace characters, as determined by nsILineBreaker. We pass a whitespace-// delimited word to nsILineBreaker if it contains at least one character// matching IsComplexChar.// We provide flags to control on a per-chunk basis where breaks are allowed.// At any character boundary, exactly one text chunk governs whether a// break is allowed at that boundary.//// We operate on text after whitespace processing has been applied, so// other characters (e.g. tabs and newlines) may have been converted to// spaces. /** * Flags passed with each chunk of text. */enum {
/* * Do not introduce a break opportunity at the start of this chunk of text. */
BREAK_SUPPRESS_INITIAL = 0x01, /** * Do not introduce a break opportunity in the interior of this chunk of text. * Also, whitespace in this chunk is treated as non-breakable. */00140BREAK_SUPPRESS_INSIDE = 0x02, /** * The sink currently is already set up to have no breaks in it; * if no breaks are possible, nsLineBreaker does not need to call * SetBreaks on it. This is useful when handling large quantities of * preformatted text; the textruns will never have any breaks set on them, * and there is no need to ever actually scan the text for breaks, except * at the end of textruns in case context is needed for following breakable * text. */00150BREAK_SKIP_SETTING_NO_BREAKS = 0x04, /** * We need to be notified of characters that should be capitalized * (as in text-transform:capitalize) in this chunk of text. */00155BREAK_NEED_CAPITALIZATION = 0x08
};
/** * Append "invisible whitespace". This acts like whitespace, but there is * no actual text associated with it. Only the BREAK_SUPPRESS_INSIDE flag * is relevant here. */
nsresult AppendInvisibleWhitespace(PRUint32 aFlags);
/** * Feed Unicode text into the linebreaker for analysis. aLength must be * nonzero. * @param aSink can be null if the breaks are not actually needed (we may * still be setting up state for later breaks) */
nsresult AppendText(nsIAtom* aLangGroup, const PRUnichar* aText, PRUint32 aLength,
PRUint32 aFlags, nsILineBreakSink* aSink); /** * Feed 8-bit text into the linebreaker for analysis. aLength must be nonzero. * @param aSink can be null if the breaks are not actually needed (we may * still be setting up state for later breaks) */
nsresult AppendText(nsIAtom* aLangGroup, const PRUint8* aText, PRUint32 aLength,
PRUint32 aFlags, nsILineBreakSink* aSink); /** * Reset all state. This means the current run has ended; any outstanding * calls through nsILineBreakSink are made, and all outstanding references to * nsILineBreakSink objects are dropped. * After this call, this linebreaker can be reused. * This must be called at least once between any call to AppendText() and * destroying the object. * @param aTrailingBreak this is set to true when there is a break opportunity * at the end of the text. This will normally only be declared true when there * is breakable whitespace at the end. */
nsresult Reset(PRBool* aTrailingBreak);
private:
// This is a list of text sources that make up the "current word" (i.e.,// run of text which does not contain any whitespace). All the mLengths// are are nonzero, these cannot overlap.struct TextItem {
TextItem(nsILineBreakSink* aSink, PRUint32 aSinkOffset, PRUint32 aLength,
PRUint32 aFlags)
: mSink(aSink), mSinkOffset(aSinkOffset), mLength(aLength), mFlags(aFlags) {}
nsILineBreakSink* mSink;
PRUint32 mSinkOffset;
PRUint32 mLength;
PRUint32 mFlags;
};
// State for the nonwhitespace "word" that started in previous text and hasn't// finished yet.// When the current word ends, this computes the linebreak opportunities// *inside* the word (excluding either end) and sets them through the// appropriate sink(s). Then we clear the current word state.
nsresult FlushCurrentWord();
nsAutoTArray<PRUnichar,100> mCurrentWord;
// All the items that contribute to mCurrentWord
nsAutoTArray<TextItem,2> mTextItems;
PRPackedBool mCurrentWordContainsComplexChar;
// True if the previous character was breakable whitespace
PRPackedBool mAfterBreakableSpace;
// True if a break must be allowed at the current position because// a run of breakable whitespace ends here
PRPackedBool mBreakHere;
};
#endif /*NSLINEBREAKER_H_*/